The goal of the proposed research is to understand in detail the role of the cap binding complex (CBC) in mRNA processing and transport. The two subunits of the CBC, Cbp20 and Cbp80, have been implicated in 3' end processing, splicing, stability, and export of mRNA. Proper gene expression depends on the success and coordination of each of these steps. Understanding the role of the CBC in proper gene expression will lead to more detailed information on how cell growth is controlled at the mRNA level. This knowledge may suggest therapies to target the uncontrolled replication of cancerous cells. Because many viruses including, HIV, exploit mRNA export pathway, information on CBC may also lead to improved antiviral therapies. Genetic and biochemical approaches will be used to identify factors that interact with CBC and to determine how these factors influence the dynamics and function of the mRNA cap binding complex in S. cerevisiae. Because the processes and components of gene expression are highly conserved in all eukaryotic cells, the information gained in studying S. cerevisiae CBC will be directly applicable to understanding the same process in mammalian cells.